STOW SOXJTH-AFEICAN GEOLOGY. 517 



In two other diggings, instead of the loose sliingle, occurs a clayey- 

 sand, mixed with small pebbles and numerous shells (Centhium &c.), 

 out of twelve species of which, seven have not yet been found on the 

 present beach. Most of the shells are broken and worn, owing no 

 doubt to their having been rolled in shallow water with, the sand 

 and small shingle in which they are imbedded. 



Purther south, after digging in a bed representing that last described 

 for about eighteen inches, the influx of spring water prevented the 

 examination being carried further. Above it was a hard limestone 

 without fossils, and above this a band of pale slate- coloured sand 

 from 9 to 18 inches thick, equivalent to the pebbly clayey sand 

 above mentioned. It is mixed with grit and small pebbles, and 

 contains numerous specimens of the straight Cerithium which occurs 

 in the equivalent bed; but all the sheUs found in it are broken and 

 waterworn. Near the Creek there is a bluish sand ; and the shells 

 in it are more perfect than in the beds previously mentioned. I had 

 no opportunity of obtaining a measurement of its greatest thickness. 

 From this particular band I have collected forty species of shells, of 

 which there are eighteen that have no living representatives on the 

 present sea-beach. I imagine that their descendants will have to be 

 looked for further to the eastward along the coast. 



There are two strata in the southern part of the section whose 

 equivalents I have not been able to trace further north. One is a 

 bright yeUow sand, from 1 to 2 feet thick, containing numerous per- 

 fect specimens of Loripes edentula (Chenu) and Mactra, with both 

 valves complete. The other is a pale slate-coloured sand, slightly 

 clayey, varying from 2 to 5 feet in thickness, and containing numerous 

 beautifully perfect shells. From the immense numbers of the 

 ATcerce found in it, I have termed it the Akera-stratum. This deposit 

 is in some places worn away, and divided in detached portions, as 

 represented at a, a, a in Section T. It is at many places capped 

 with a layer of waterworn fragments of shell-limestone, pieces 

 of sheU-grit containing small pebbles, and also waterworn shells of 

 the present ocean. These last were, of course, left in the position in 

 which they are found during the retreat of the sea to its present level. 

 The number of species of shells that I have already obtained from 

 this stratum is 71 ; of these, 27 have not been found on the present 

 coast, and of 10 others it is doubtful whether they are still living 

 in the neighbouring bay. The straight Cerithium, the Pectunculus, 

 and others have sometimes been picked up by shell-collectors on 

 the beach, mixed with recent shells ; but, possessing none of the 

 fresh appearance of more recent shells, they have always borne 

 evidence of having been disinterred. 



§ 3. Pliocene or Postpliocene Strata {Baised Beaches) on the Coast 

 and Inland. — ^The next deposits, so far as at present known, in suc- 

 cession to these, are shell-banks that are not only found along 

 the coast, forming a raised sea-beach, as on the south side of the 

 Zwartkops Eiver's mouth, but also extending inland as raised banks 

 nearly as far as Cradocktown. They are evidently far more exten- 

 sive than those we have just been considering. The principal parts 



